Jaffe points to recent research suggesting equities become less risky the longer they are held, so long as the investment is held in stock indexes or baskets, not individual stocks.

The findings from David Blanchett of Morningstar and professors Michael Finke of Texas Tech University and Wade Plau of American College involve "time diversification" of stocks rather than typical asset diversification across stocks, bonds and international holdings.
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"The longer your holding period, the more aggressive you really can and should be. For an investor with an infinite time horizon — let's just say 20 or 30 years — probably the lowest risk long-term investment for that investor is actually stocks," Blanchett told Jaffe.

The research covered 20 countries and over 100 years in the markets for those countries.

"The kicker is that people tend to look at their account statements on some regular intervals and they feel that pain long term," Blanchett added. "But really if you were going to buy something, put it in a lockbox and then come back and check it 20 years from now, hands down that would be stocks."

The time diversification strategy flies in the face of common investor belief that the longer one sticks with a stock portfolio, the more that market upheavals, downturns and corrections will affect performance — kind of like "strapping yourself to a rollercoaster, which does not guarantee that it will be up — or even back to your starting point — when the time comes that you have to get off," Jaffe wrote.

To overcome the queasiness over a buy-and-hold-for-decades decision, Blanchett suggested investors might consider dividing their holdings between long-term money and short-term money. While that may not be the most profitable strategy, he conceded it would make many people comfortable.

For the poll, some of the most prominent investment bloggers were asked about their outlook for the S&P 500 for the next 30 days. The latest reading: 48 percent bullish, 28 percent neutral and 25 percent bearish.

But Ralph Acampora, senior managing director at Altaira Ltd. and a noted technical analyst of the stock market, was slightly more muted in his enthusiasm on Twitter this week.

"The market exhibits continued upside momentum. The real test is close at hand — we need to see new highs in the market's leading indexes," Acampora tweeted.